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LMH0344 SDI inputs

Other Parts Discussed in Thread: LMH0344, TPD1E05U06, TPD2EUSB30A, TPD4E110

The data sheet indicates that max voltage is -0.3v to 3.6v @ the SDI pins, we typically have transients, in the past I have added low cap. TVS and/or current limiting resistors to mitigate the transients. The DS lists a 1.3k input imped. and ESD protection. Could you let me know if an +/-8-10v 70uS pulse would harm the device?  On other devices if you limit the current to <10-15mA the ESD diodes would be able to handle the transient.

Thanks,

Larry

  • Hi Larry,
    LMH0344 has not been tested under this condition and this is beyond data sheet spec. I am not sure about the load capacitance of the TVS you are using but this may effect the performance of the device since it lowers the signal bandwidth. In general, as you noted, if you limit the current to 10-20mA the ESD diodes and short circuit protection can handle this.

    Regards,,nasser
  • Hi Nassar,


    Thanks for the response a further question The DS lists a 1.3k input imped. and ESD protection, could you provide the order? I would suspect the ESD diodes are more or less at the pin and then the device has it's 1.3k input impedence after the diodes?

    Thanks,
    Larry
  • Hi Larry,

    You are correct we have the ESD ring first and then the device has 1.3K Ohm input impedance.

    Regards,,nasser
  • Hi Larry,

    Don't know if adding low insertion capacitance ESD diodes would be of interest, but here are some examples:

    TPD1E05U06 - 1 Channel Ultra Low Capacitance IEC ESD Protection Diode,  0.4pF
    TPD2EUSB30A - 2 Channel ESD/ Surge Solution for High Speed, Low Voltage Interface,  0.7pF
    TPD4E110 - Quad Channel ESD Protection Solution for SuperSpeed Interface (up to 6 GBPS),  0.5pF
    I will be at Rockwell-Collins the week of the 18th in case you'd like a face-to-face.
    Cheers!
    Mark Pearson
  • Re-posting.

    The last post came out really goofy.
    Don't know if adding low insertion capacitance ESD diodes would be of interest, but here are some examples:

    TPD1E05U06 - 1 Channel Ultra Low Capacitance IEC ESD Protection Diode, 0.4pF
    TPD2EUSB30A - 2 Channel ESD/ Surge Solution for High Speed, Low Voltage Interface, 0.7pF
    TPD4E110 - Quad Channel ESD Protection Solution for SuperSpeed Interface (up to 6 GBPS), 0.5pF

    I will be at Rockwell-Collins the week of the 18th in case you'd like a face-to-face.

    Cheers!

    Mark Pearson
  • Hi Mark,

    Thanks for the info. I do have a device on the lines a GBLC03 low cap. TVS.

    If you have other devices we can certainly discuss those.

    Thanks,

    Larry